Re: st: replicate matrix elements

["Brian P. Poi" <bpoi@stata.com>]

Robert Duval wrote:
> Hi,
>
> Is there a command in Stata to construct a vector
>
> A= (1,1,1,4,4,4)
>
> out of an original vector (1,4) by replicating its elements?
>
> In R this would be done with
>
> rep(c(1,4), each=3, times=1)
>
> Any suggestions will be appreciated
> robert
> *

One way is to use the Kronecker product with a row vector of ones whose length is the number of times you want to replicate each element.

In Mata:

: a = (1,4)
: b = J(1,3,1)
: a#b
       1   2   3   4   5   6
    +-------------------------+
  1 |  1   1   1   4   4   4  |
    +-------------------------+

Stata's older -matrix- matrix commands also use # for the Kronecker product:

. mat a = (1,4)
. mat b = J(1,3,1)
. mat c = a#b
. mat list c


   -- Brian Poi
   -- brian@poiholdings.com
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